Suspension concentrate formulation containing pyrimethanil

ABSTRACT

The invention provides an aqueous SC formulation comprising: a) 50 to 80% w/v pyrimethanil; b) 0.2 to 5% w/v of a polyoxyethylene-polyoxypropylene block copolymer surfactant; and c) 0.2 to 5% w/v of a naphthalene formaldehyde condensate surfactant. We have found that formulations according to the invention surprisingly do not solidify when milled during manufacture and also exhibit a low propensity to crystallise when stored for prolonged periods.

This application is a 371 of PCT/GB99/02437 filed Jul. 9, 1999.

This invention relates to liquid formulations of pyrimethanil andmethods for their preparation. In particular, the invention relates tosuspension concentrate (SC) formulations that contain high proportionsof solid pyrimethanil.

Commercial SC formulations comprising the fungicide pyrimethanil includeMythos® and Scala®. Typically these formulations contain not more than40% w/v pyrimethanii. Increasing the amount of pyrimethanil in theseformulations above 40% would be advantageous, since it would reduce thecost of transporting a given amount of active ingredient. These savingswould be particularly significant where pyrimethanil is transported toremote places where distribution is difficult, such as to tropicalzones. However, increasing the concentration of pyrimethanil in theseformulation leads to milling problems during manufacture andcrystallisation during storage.

It is therefore an object of the invention to devise an SC formulationsystem containing concentrations of pyrimethanil significantly greaterthan 40% without experiencing the abovementioned problems.

According to a first aspect, the invention provides an aqueous SCformulation comprising a) 50 to 80% w/v pyrimethanil, preferably 60 to80% w/v; b) 0.2 to 5% w/v of a polyoxyethylene-polyoxypropylene blockcopolymer surfactant, preferably 0.3 to 1.5%; and c) 0.2 to 5% w/v of anapthalene formaldehyde condensate surfactant, preferably 0.3 to 1.5%.

We have found that formulations according to the invention surprisinglydo not solidify when milled during manufacture and also exhibit a lowpropensity to crystallise when stored for prolonged periods.

Throughout this specification, unless the context requires otherwise,the word “comprise”, or variations such as “comprises” or “comprising”will be understood to imply the inclusion of a stated integer or groupof integers, but not the exclusion of any other integer or group ofintegers including method steps.

Preferably component b) has a molecular weight of 6000 to 14000,especially 9000 to 13000. Further, component b) contains 20 to 80% w/wof polyoxyethylene, especially 40 to 80%. In particular, the molecularweight of component b) is nominally 12000 and the amount ofpolyoxyethylene is nominally 70% w/w.

Preferably component c) is a salt, particularly the sodium salt.

Preferably the formulation also comprises a dispersant, such as apolymethyl methacrylate-polyethylene glycol graft copolymer, preferablyhaving a molecular weight of 20000 to 30000, in amounts of 1 to 10% w/v,preferably 3 to 8%.

A particularly preferred SC formulation comprises a) approximately 60%w/v pyrimethanil, b) approximately 0.5% w/v of anethenylenoxy-propyleneoxy block co-polymer surfactant, c) approximately1% w/v of sodium naphthalene formaldehyde condensate surfactant, d)approximately 5% w/v polymethyl methacrylate-polyethylene glycol graftcopolymer, e) approximately 6% w/v propylene glycol and f) approximately37.5% w/v water.

Our invention is illustrated, by way of example only, with reference tothe following.

EXAMPLES

A number of formulations of differing composition were prepared. Table 1shows the components and their concentrations in w/v. In most cases thecomponents are given as their trade name. Their chemical composition andmajor function are as follows.

Atlox 4894 is polyoxyethylene alkyl ether (NPE-free); acts as adispersant and wetter.

Atlox 4913 is polymethyl methacrylate-polyethylene glycol graftcopolymer; acts as a dispersant.

Atlox 5406B is a blend of anionic and nonionic surfactants; acts as adispersant and wetter.

Morwet D425 is sodium naphtalene formaldehyde condensate; acts as adispersant and viscosity modifier.

Synperonic PE F127 is a polyoxyethylene-polyoxypropylene blockcopolymer; acts as a dispersant and wetter.

Lauropal X1003 is an ethoxylated alcohol; acts as a wetter.

Polyfon H is sodium lignosulphonate; acts as a dispersant.

Tegopren 5840 is a copolymer consisting of polymethyl siloxanes andpolyoxyethylene-polyoxypropylene segments; acts as a wetter.

Reax 85A is sodium lignosulphonate; acts as a dispersant.

Surfynol 104-E is tetramethyl decynediol and ethylene glycol; actsmainly as a wetter.

Surfynol 420 is polyoxyethylene (1.3 moles) tetramethyl decynediol; actsas a wetter.

Arylan SBC25 is sodium dodecylbenzene sulphonate; acts as a wetter.

Witconol NS 500 LQ is a nonionic surfactant blend; acts as a dispersant.

Synperonic 91/6 is polyoxyethylene (6 moles) synthetic primary C₉/C₁₁alcohol; acts as a wetter.

Emcol CC9E is polypropylene glycol (9 moles) diethylmonium chloride;acts as a dispersant and viscosity modifier.

Aerosol OT/S is dioctyl sodium sulfosuccinate; acts as a wetter.

Each Formulation was Prepared as Follows.

Method

All components (except aqueous Kelzan pregel) are dispersed using a highspeed mixer. The dispersion is passed through a bead mill under suchconditions to achieve the desired particle size distribution andviscosity. Aqueous Kelzan pregel is added to the milled suspension.

Formulations 1 and 2 are formulations of the invention. The remainingformulations are by way of comparison. Each formulation was analysed interms of milling performance and extent of crystallisation after 2 weeksstorage at 54° C. The results are as follows

Milling Performance

Formulations 3 to 6, 13 to 18, 20 and 24 solidified during milling.

Formulations 1, 2, 7 to 12, 19, 21, 22 and 23 exhibited no millingproblems.

Extent of Crystallisation After Storage at 54° C.

Formulations 7 to 12, 19, 21, 22 and 23 exhibited crystal growth after 2weeks at 54° C., this was particularly marked with 11, 19, 21 and 23.

Formulation 2 showed very slight crystallisation.

Formulation 1 showed no crystal growth.

TABLE 1 Formulation number 1 2 3 4 5 6 7 8 9 10 11 12 Pyrimethanil (99%)606 606 606 606 606 606 606 606 606 606 606 606 Propylene glycol 60 6060 60 60 60 60 60 60 60 60 60 DC 1520 antifoam 1 1 1 1 1 1 1 1 1 1 1 1Kelzan 1 1 1 1 1 1 1 1 1 1 1 1 Proxel XL2 1 1 1 1 1 1 1 1 1 1 1 1 Atlox4913 50 50 50 50 50 50 50 50 50 50 50 50 Tegopren 5840 — — 15 — — — — —— — — — Reax 85 A — — — 15 — — — — — — — — Surfynol 104-E — — — — 15 — —— — — — — Surfynol 420 — — — — — 15 — — — — — — Morwet D425 10 5 — — — —— — — — — Synperonic PE F127 5 10 — — — — 10 10 5 — — Arylan SBC 25 — —— — — — — — 15 — — Witconol NS 500 LQ — — — — — — — — — 15 — Emcol CC 9E— — — — — — — 1 — — 1 — Aerosol OT/S — — — — — — — — — — — 15 Atlox 4894— — — — — — — — — — — — Atlox 5406B — — — — — — — — — — — — LauropalX1003 — — — — — — — — — — — — Polyfon H — — — — — — — — — — — —Synperonic 91/6 — — — — — — — — — — — — Water 366 366 366 366 366 366371 370 376 366 365 366 Formulation number 13 14 15 16 17 18 19 20 21 2223 24 Pyrimethanil (99%) 606 606 606 606 606 606 606 606 606 606 606 606Propylene glycol 60 60 60 60 60 60 60 60 60 60 60 60 DC 1520 antifoam 11 1 1 1 1 1 1 1 1 1 1 Kelzan 1 1 1 1 1 1 1 1 1 1 1 1 Proxel XL2 1 1 1 11 1 1 1 1 1 1 1 Atlox 4913 — 20 — 10 30 50 20 50 50 50 50 50 Tegopren5840 — — — — — — — — — — — Reax 85 A — — — — — — — — — — — Surfynol104-E — — — — — — — — — — — 7.5 Surfynol 420 — — — — — — — — — — — 7.5Morwet D425 — — — — — — 15 15 — — — Synperonic PE F127 — — — — — — — — —15 — Arylan SBC 25 — — — — — — — — — — — Witconol NS 500 LQ — — — — — —— — — — — Emcol CC 9E — — — — — — — — — — — Aerosol OT/S — — — — — — — —— — — Atlox 4894 50 30 — 30 — — 50 — — — — Atlox 5406B — — 50 10 20 — —— — — — Lauropal X1003 — — — — — — — — 15 — — Polyfon H — — — — — — — —— — 15 Synperonic 91/6 — — — — — 15 — — — — — Water 381 381 381 381 381366 346 366 366 366 366 366

What is claimed is:
 1. An aqueous SC formulation comprising a) 50 to 80%w/v pyrimethanil, b) 0.2 to 5% w/v of a polyoxyethylene-polyoxypropyleneblock copolymer surfactant, and c) 0.2 to 5% w/v of a napthaleneformaldehyde condensate surfactant.
 2. A formulation according to claim1 wherein component b) has a molecular weight of 6,000 to 14,000.
 3. Aformulation according to claim 1 wherein component b) has a molecularweight of 9,000 to 13,000.
 4. A formulation -according to claim 1wherein component b) contains 20 to 80% w/w of polyoxyethylene.
 5. Aformulation according to claim 1 wherein component b) contains 40 to 80%w/w of polyoxyethylene.
 6. A formulation according to claim 1 whereinthe molecular weight of component b) is about 12000 and the amount ofpolyoxyethylene is about 70% w/w.
 7. A formulation according to anypreceding claim 1 wherein component c) is a salt.
 8. A formulationaccording to claim 1 which further comprises a polymethylmethacrylate-polyethylene glycol graft copolymer dispersant.
 9. Aformulation according to claim 8 wherein the dispersant has a molecularweight of 20,000 to 30,000, and is present in an amount of 1 to 10% w/v.10. A formulation according to claim 1 comprising a) 60 to 80% w/vpyrimethanil, b) 0.3 to 1.5 w/v of a polyoxyethylene-polyoxpropyleneblock copolymer surfactant, and c) 0.3 to 1.5 w/v of a napthaleneformaldehyde condensate surfactant.
 11. A formulation according to claim10 wherein component b) has a molecular weight of 6,000 to 14,000 andcontains 20 to 80% w/w of polyoxyethylene.
 12. A formulation accordingto claim 11 wherein component b) has a molecular weight of 9,000 to13,000 and contains 40 to 80% w/w of polyoxyethylene.
 13. A formulationaccording to claim 12 wherein component c) is a salt.
 14. A formulationaccording to claim 12 which further comprises a polymethylmethacrylate-polyethylene glycol graft copolymer dispersant.
 15. Aformation according to claim 14 wherein the dispersant has a molecularweight of 20,000 to 30,000, and is present in an amount of 1 to 10% w/v.16. A formulation according to claim 15 comprising a) approximately 60%w/v pyrimethanil, b) approximately 0.5% w/v of anethenylenoxy-propyleneoxy block co-polymer surfactant, c) approximately1% w/v of sodium naphthalene formaldehyde condensate surfactant, d)approximately 5% w/v polymethyl methacrylate-polyethylene glycol graftcopolymer, e) approximately 6% w/v propylene glycol and f) approximately37.5% w/v water.
 17. A formulation according to claim 16 wherein themolecular weight of component b) is nominally 12,000 and the amount ofpolyoxyethylene is nominally 70% w/w.
 18. A formulation comprising a)approximately 60% w/v pyrimethanil, b) approximately 0.5% w/v of anethenylenoxy-propyleneoxy block co-polymer surfactant, c) approximately1% w/v of sodium naphthalene formaldehyde condensate surfactant, d)approximately 5% w/v polymethyl methacrylate-polyethylene glycol graftcopolymer, e) approximately 6% w/v propylene glycol and f) approximately37.5% w/v water.